Cell repair and death
Cellular repair mechanisms and cell death
Exposure to toxic drugs does not necessarily lead to cell death or organ failure, because the cell has many kinds of repair mechanisms at its disposal. At the level of damaged proteins or lipids, the cell can restore them by enzymatic reactions (reduction) or refolding of proteins. If repair is not possible, damaged macromolecules can be metabolised.
For the repair of DNA, the cell has different mechanisms available. Missing nucleotides can be replaced and damaged DNA can be excised and repaired. See also the mechanism of trabectedin.
When repair mechanisms fail, the cell can go into programmed cell death (apoptosis). During this delicate process, the cell undergoes structured self-destruction by shrinkage, nuclear condensation and formation of the characteristic apoptotic bodies. At the surface, an apoptotic cell displays specific proteins which make the cell recognizable for macrophages and subsequent phagocytosis.
When the cell damage is severe and happens rapidly, the apoptotic programme cannot be performed. In this case the cell undergoes necrosis. During necrosis the cellular content is digested, followed by swelling of the cell and rupture of the membranes. In contrast to apoptosis, necrosis attracts inflammatory cells and thus has a greater impact on organ failure.